1. Field of the Invention
This invention relates to an apparatus for adjusting the tool length of a panel forming machine and, more particularly, to an apparatus for changing a die to alter the effective die width (or the upper die length) of the upper die to the desired bending length for bending a sheet metal plate.
2. Description of the Prior Art
Metal plates, the edge of which is bent in U or Z shape, are employed in a cabinet, a display case, a vending machine, a refrigerator, a panel, a sink, or a switchboard. In order to bend the edge in this shape, the side edges of a sheet metal is ordinarily bent. The sheet metal is then turned in a plane, an upper die is matched to the bent width to the inside of the bent short side of the metal, and the edge of the long side is bent. When the long side of the metal is, for example, bent by a wing bender or press brake, it is necessary to provide a length of the upper die obtained by subtracting the thickness corresponding to two sheets by the length of the long side since there is a rise produced by the previously bent short side. It is further necessary to prepare a number of upper dies of different widths and to change the top tools whenever the width of a work varies, which disadvantageously requires an excessive labor in the exchange. In other words, the length adjustment by resetting the central tools results in long setting time and requires a number of tools of different lengths.